Artificial sphincter

ABSTRACT

With an object of providing an artificial sphincter for which repeated shape changes are possible, and for which the quantity of shape change is sufficient so as to be used as a substitute for a large natural sphincter, an artificial sphincter  11  that opens and closes, as required, either the anus of a living body or part of the intestine  19  led outside the body is provided, wherein this artificial sphincter  11  comprises a pair of shape memory alloy elements  13  that change reversibly between two opposite shapes upon changes in temperature and hinges  15  that link the shape memory alloy elements  1  together in a cylindrical shape.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an artificial sphincter used,for example, when the anal sphincter has been removed or when there hasbeen a decline in the functioning of a sphincter.

[0003] 2. Description of the Related Art

[0004] Conventionally, in cases such as when development of the analsphincter is incomplete due to infantile rectal/anal malformation orwhen the anal sphincter is removed due to colonic cancer as an adult, anartificial anus is used.

[0005] An artificial anus commonly used conventionally is formed bysewing the intestine so as to open out at the surface of the body, andthen attaching a pouch to the surface of the body so as to cover thisintestinal opening.

[0006] With all pouches available on the market, the whole or part ofthe pouch must be replaced after defecation, and an unpleasant odor mayleak out. Due to such problems, there is a drawback that everyday sociallife becomes troublesome.

[0007] There are artificial anuses having a stopper for which pouchreplacement is not necessary. With these artificial anuses, a T-shapedcover is set into a flange that covers the aforementioned intestinalopening. There is an inconvenience in that, every time defecationoccurs, the cover must be removed and then reattached. Moreover, thereis also the possibility of excrement or gas leaking out from gapsbetween the cover and the opening.

[0008] To resolve the drawbacks of the pouch method, an artificial anushas been proposed in which an intestine opening/closing portioncomprising a shape memory alloy is provided around an intestinal openingin the body, and the intestinal opening on the surface of the body isheated by passing a current from a battery embedded in the body, thuschanging the shape of the shape memory alloy and opening/closing theintestinal opening (Japanese Patent Application Laid-open No. H4-319349;hereinafter referred to as ‘Prior Art Document 1’).

[0009] With the artificial anus of Prior Art Document 1, the scope ofactivity of the patient is widened, with no removal or replacement beingnecessary after defecation, and moreover because a shape memory alloy isused, a sufficient constricting force can be generated, resulting inexcrement leakage and unpleasant odors being prevented.

[0010] With an artificial anus such as that disclosed in Prior ArtDocument 1, in which an intestine opening/closing portion comprising ashape memory alloy is provided around an intestinal opening in the body,and the intestinal opening on the surface of the body is heated bypassing a current from a battery embedded in the body, thus changing theshape of the shape memory alloy and opening/closing the intestinalopening, a ring-shaped shape memory alloy element is used, and thestructure is such that the intestinal opening is closed when the shapememory alloy is squashed flat. The power source for heating is coveredin a case of a material having good affinity with living bodies, such asa polysulfone, and a small battery and a push switch are providedinside.

[0011] In this way, heating is carried out by passing a current from thesmall battery embedded in the body, thus changing the shape of the shapememory alloy and opening/closing the intestinal opening.

[0012] However, the shape memory alloy (SMA) ring used here has locallylarge distortion and poor repetition characteristics, making itdifficult to change the shape repeatedly. Moreover, when a shape memoryalloy element is embedded in a narrow region, namely an intestinalopening on the surface of the body, the intestine is subjected to alocal force, and there is thus a risk of damage to this part of thebody.

[0013] Moreover, the power source for heating is embedded between theskin and the muscularis, meaning that replacement when the small batteryhas been exhausted is troublesome. In particular, the small battery andthe push switch that constitute the power source for heating areconnected to the shape memory alloy (SMA) ring via a lead wire, and sothe choice of installment location is somewhat limited.

[0014] Furthermore, the lead wire must be a certain length, and there isa risk of infection along this part.

[0015] One could also envisage transmitting electrical power into thebody from a power source outside the body via a lead wire, but thenthere would be a risk of infection from the electrode part passingthrough to the outside of the body.

[0016] Moreover, even in the case of a 2-way shape memory alloy, it isdifficult to achieve a quantity of shape change from the state in whichthe ring is squashed flat such that the opening opens to a sufficientsize for unimpeded defecation to be possible.

SUMMARY OF THE INVENTION

[0017] It is an object of the present invention to provide an artificialsphincter for which repeated shape changes are possible, and for whichthe quantity of shape change is sufficient so as to be used as asubstitute for a natural sphincter.

[0018] It is another object of the present invention to provide anartificial sphincter that eliminates inconveniences of theaforementioned conventional examples, and for which electrical powersupply is possible without passing a lead wire through the skin, thusavoiding risk of infection.

[0019] According to one aspect of the present invention, there isprovided an artificial sphincter having an opening/closing portion foropening and closing is obtained, wherein the opening/closing portion hasa pair of elongated memory alloy elements that change reversibly betweenopposite shapes upon changes in temperature.

[0020] Moreover, according to another aspect of the present invention,there is provided an artificial sphincter comprising a shape memoryalloy opening/closing portion and temperature controlling heaters isobtained, wherein electrical power is supplied to the temperaturecontrolling heaters by a percutaneous electrical power transmissionsystem having a coil on the side connected to the power source as aprimary coil and a coil on the side connected to the load as a secondarycoil. The electrical power may be supplied without using a lead wire.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 is a schematic drawing showing the principal parts of anartificial sphincter according to a first embodiment of the presentinvention;

[0022]FIG. 2 is a schematic drawing showing shape changing of a shapememory plate used in the artificial sphincter of FIG. 1.

[0023]FIG. 3 is a drawing showing a state in which the artificialsphincter of FIG. 1 is constricting the intestine;

[0024]FIG. 4 is a drawing showing a state in which the artificialsphincter of FIG. 1 is not constricting the intestine;

[0025]FIG. 5 is a schematic drawing showing an example of application ofthe artificial sphincter of FIG. 1 to a live animal experiment;

[0026]FIG. 6 is an explanatory drawing showing an artificial sphincteraccording to a second embodiment of the present invention;

[0027]FIG. 7 is a perspective view of the shape memory alloyopening/closing portion of the artificial sphincter of FIG. 6;

[0028]FIG. 8 is a plan view of the shape memory alloy opening/closingportion of the artificial sphincter of FIG. 6;

[0029]FIG. 9 is a side view of the shape memory alloy opening/closingportion of the artificial sphincter of FIG. 6; and

[0030]FIG. 10 is an explanatory drawing showing a live animal experimentusing a manufactured artificial sphincter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Description will be made as regards the preferred embodimentaccording to the present invention with reference to FIG. 1-10.

[0032] (First Embodiment)

[0033] As shown in FIG. 1, an opening/closing portion 11 of anartificial sphincter according to a first embodiment comprises a pair ofplate-like shape memory alloy elements (hereinafter referred to as‘shape memory plates’) 13 each having a 2-way shape memory property, andhinges 15 provided so as to join together end parts of the shape memoryplates 13. The opening/closing portion 11 is attached around theintestine 19 of a human or animal inside the body near to an intestinalopening 17.

[0034] For the opening/closing portion 11 of the artificial sphincter,Ti—Ni alloy plates (Ni content 50.4 at %) of thickness 0.8 mm, length100 mm and width 20 mm are given a 2-way shape memory property. The2-way shape memory property is obtained by subjecting the plates tosolution heat treatment at 700° C. for 30 minutes, and then, whilerestrained at a curvature of R40 mm, to aging heat treatment at 400° C.for 100 hours. If heated to 40° C., these plates return to the shape atthe time of the aging heat treatment at 400° C. for 100 hours. If,cooled to body temperature, the plates change shape, bending backwardsin the opposite direction. In each case, the curvature is about R40 mm.

[0035] Two 2-way shape memory plates 13 prepared in this way are used,and these 2-way shape memory plates 13 are linked to the intestine 19near to the intestinal opening in a cylindrical shape using the hinges15 in such a way that the inside of each of the 2-way shape memoryplates 13 is in the direction of the restraining that was carried outduring the aging heat treatment, thus forming the opening/closingportion 11 of the artificial sphincter.

[0036] As shown in FIG. 2, when heated and cooled,-the shape memoryplates 13 change reversibly between two opposite shapes. Specifically,in FIG. 2, a shape memory plate 13 changes between two arc shapes thatbend in opposite directions.

[0037] Following is a description of the operation of the artificialsphincter with reference to FIGS. 3 and 4.

[0038]FIG. 3 shows the normal state, in which the 2-way shape memoryplates 13 are each bent in the opposite direction to the direction ofthe restraining that was carried out during the aging heat treatment.The intestine 19 is thus constricted by the opening/closing portion 11.

[0039]FIG. 4, on the other hand, shows the state during defecation. The2-way shape memory plates 13 have each been heated and have returned tobeing bent in the direction of the restraining that was carried outduring the aging heat treatment, and hence the constricting force on theintestine 19 has been lost. Here, the heating method was to pass anelectric current, but heating through electromagnetic induction, warmwater, a current of warm air or the like is also possible.

[0040] As described above, with the artificial sphincter according tothe first embodiment of the present invention, two shape memory plates13 are linked together with hinges 15, and as a result the quantity ofdeformation of the 2-way shape memory plates 13 can be reduced, andmoreover a quantity of shape change can be achieved such that theopening opens to a diameter (25 mm) sufficient for unimpeded defecation.

[0041] Moreover, the two shape memory plates 13 in the first embodimentof the present invention can be easily separated, and hence there is noneed to sever the intestine during installation.

[0042] Here, the shape memory alloy used for the 2-way shape memoryplates is not limited to being a Ti—Ni alloy, but may also be a Ti—Ni—Xalloy (X=Cr, V, Cu, Fe, Co or the like) in which a third element isadded, or any of various other kinds such as a Cu shape memory alloy oran Fe shape memory alloy.

[0043] Next, a description will be given of an example of application ofthe artificial sphincter according to the first embodiment of thepresent invention.

[0044] As shown in FIG. 5, sponge rubber 23 is provided in the regionswhere the artificial sphincter 21 comes into contact with the intestine.This sponge rubber 23 acts as heat insulation and cushioning.

[0045] As heating means, formal wires 20 (diameter 0.2 mm) are laid overthe shape memory plates 13. These formal wires 20 heat by means of Jouleheat.

[0046] A live animal experiment was carried out using a sheep, with theartificial sphincter being attached to the small intestine, which isconsidered to be about the same size as the colon of a human. Firstly,hydrostatic pressure was applied using an injector while at lowtemperature to produce a state the same as when the actual abdominalpressure is applied, and the ability of the artificial sphincter 21 toclose the intestine was evaluated. As a result, it was verified that theintestine is completely closed even at a pressure of 50 mmHg (6.65 kPa),which is greater than 20 mmHg (2.66 kPa), the envisaged abdominalpressure of a human.

[0047] Next, with the hydrostatic pressure acting as a load, a directcurrent was passed through the heaters to heat the shape memory plates,and it was verified whether the artificial sphincter operated to openthe intestine and whether internal fluids flowed out. As a result, itwas found that internal fluids did indeed flow out with no problem dueto the opening operation. It was also found that, after the current wasstopped and natural cooling was allowed to occur, the valve closedcompletely, and thus that there is no problem with the opening/closingoperation.

[0048] As described above, according to the first embodiment of thepresent invention, an artificial sphincter that opens and closes, asrequired, either the anus of a living body or part of the intestine ledoutside the body can be obtained, wherein this artificial sphinctercomprises shape memory alloy elements that change reversibly between twoopposite shapes upon changes in temperature and hinges that link theseshape memory alloy elements together in a cylindrical shape.

[0049] The artificial sphincter according to the first embodiment of thepresent invention comprises two shape memory alloy elements linkedtogether with hinges, and hence the quantity of deformation of the shapememory alloy elements can be reduced, and moreover a quantity of shapechange can be achieved such that the opening opens to a diametersufficient for unimpeded defecation.

[0050] (Second Embodiment)

[0051] Referring to FIG. 6, an artificial sphincter according to asecond embodiment of the present invention comprises a shape memoryalloy opening/closing portion 25 and temperature controlling heaters 27,wherein electrical power is supplied to the temperature controllingheaters 27 by a percutaneous electrical power transmission system 33having a coil on the side connected to the power source 53 as a primarycoil 29 and a coil on the side connected to the load as a secondary coil31. In this embodiment, the electrical power is supplied without using alead wire.

[0052] Starting with a description of the shape memory alloyopening/closing portion 25, as shown in FIGS. 7 to 9, thisopening/closing portion 25 comprises two shape memory alloy plates 35 asa pair of shape memory alloy elements that each change reversiblybetween two opposite shapes upon changes in temperature, and cylindricalhinges 37 that link together the end parts (at both ends) of these shapememory alloy plates 35 in such a way as to allow free rotation.

[0053] The shape memory alloy plates 35 are, for example, Ti—Ni alloyplates (Ni content 50.4 at %) that have been given a 2-way shape memoryproperty and are generally of thickness 0.5 to 2.0 mm, length 10 to 120mm and width 5 to 30 mm.

[0054] Here, the shape memory alloy used for the 2-way shape memoryplates is not limited to being a Ti—Ni alloy, but may also be, forexample, a Ti—Ni—X alloy (X=Cr, V, Cu, Fe, Co or the like) in which athird element is added to a Ti═Ni alloy, or any of various other kindssuch as a Cu shape memory alloy or an Fe shape memory alloy.

[0055] In one example, the shape memory alloy plates 35 are Ti—Ni alloyplates (Ni content 51 at %) of width 18.5 mm, length 70 mm and thickness0.5 mm.

[0056] To give these plates a 2-way shape memory property, solution heattreatment was carried out at 700° C. for 30 minutes, and then, with theplates restrained at a curvature of R40 mm, aging heat treatment wascarried out at 400° C. for 100 hours. If heated to 40° C., the platesreturn to the shape at the time of the aging heat treatment at 400° C.for 100 hours. If cooled to body temperature, the plates change shape,bending backwards in the opposite direction.

[0057] Two 2-way shape memory alloy plates 35 obtained in this way wereprepared, and were linked in a cylindrical shape near to the intestinalopening using parts of the hinges 37 in such a way that the inside ofeach of the 2-way shape memory alloy plates 35 was in the direction ofrestraining at the time of the aging heat treatment, thus forming theopening/closing portion 25 as an artificial sphincter.

[0058] The temperature controlling heaters 27 were stuck to the outsidesof the shape memory alloy plates 35, and a double layer of medical felt(Bard PTFE felt made by Medicon) was stuck to the surface of each of thetemperature controlling heaters 27 so as to thermally insulate the bodytissue from the artificial sphincter and obtain biocompatibility.

[0059] Moreover, sponge rubber 41, which acts as heat insulation andcushioning, was placed on the inside of the portions that come intocontact with the intestine 39, which is the alimentary canal. A medicalsilicone (Silastic MDX4-4210 made by Toray-Dow Silicone Asia) wasapplied onto surfaces of the sponge rubber 41 to improvebiocompatibility and heat insulation properties.

[0060] The shape memory alloy plates 35 can also be covered with aheat-insulating material 43 having good biocompatibility and high heatinsulation performance so that there are no adverse effects on thesurrounding body tissue. Examples of this heat-insulating material 43include cork, felt, a polyurethane, a silicone film, or an MPC polymerfilm.

[0061] The hinges 37 each comprise rotating cylinders 37 a, a pin 37 band a retaining ring 37 c. A material that does not deform much onheating and has good biocompatibility, such as a polycarbonate orhydroxyapatite can be used in the hinges 37. Moreover, metal hinges forwhich the surfaces are coated with titanium, hydroxyapatite or the liketo improve biocompatibility may also be used.

[0062] A percutaneous electrical power transmission system 33 is used asthe power supply for the temperature controlling heaters 27. Regardingthe primary coil 29 connected to the power source and the secondary coil31 connected to the load (i.e. on the side of the temperaturecontrolling heaters 27), the windings have a structure in which Litzwire comprising a plurality of copper wires of diameter 0.1 mm twistedinto a bundle is wound into a flat spiral shape.

[0063] Moreover, in addition to this flat spirally wound structure, theprimary coil 29 and the secondary coil 31 each have a magnetic bodymounted on the surface of the flat spirally wound coil on only one side,wherein this magnetic body has a structure in which Co zeromagnetostrictive amorphous magnetic wires of diameter about a few tensof μm are arranged radially.

[0064] The primary coil 29 and the secondary coil 31 are positioned suchthat the magnetic wires mounted on one side of each of the coilssandwiches the windings of the coils, and electrical power istransmitted non-contactingly by means of electromagnetic inductionbetween the two coils.

[0065] During the percutaneous electrical power transmission, theprimary coil 29 is positioned on top of the skin 45 of the living bodyand the secondary coil 31 below the skin 45 in an approximately parallelcoaxial position, and electrical power is supplied into the body fromthe outside without using a lead wire, i.e., in a cordless fashion.

[0066] Note that the artificial sphincter may be used to open and closethe urethra instead of the intestine 39, in which case the shape of andaging treatment conditions for the shape memory alloy plates 35 and theshape of the hinges 37 may be changed appropriately.

[0067] Moreover, one can also envisage permanently installing theprimary coil 29 in advance in, for example, a building, such as atoilet. The location of such a toilet can be chosen to be somewhereoften used by a patient having the artificial sphincter of the presentinvention embedded within his/her body, for example the patient's homeor company, a hospital or a school. By permanently installing theprimary coil 29 in this way, the nuisance of having to carry the primarycoil 29 around is eliminated, and even when a patient has lost his/herprimary coil 29 and a replacement can not be obtained immediately,measures can be taken easily.

[0068] The primary coil 29 and the power source 53 may be formed into asingle integral body so as to be conveniently carried by the patient.

[0069] Furthermore, as another embodiment, it is also possible for boththe primary coil 29 and the secondary coil 31 to be embedded in theliving body. In this case, a battery is suitable as the power sourceconnected to the primary coil 29, and even if the secondary coil 31 andthe shape memory alloy opening/closing portion 25 are installed in partof the body for which a general anesthetic is necessary, the primarycoil 29 can be embedded in part of the body such that replacement ispossible under only a local anesthetic.

[0070] Following is a description of results of experiments carried outto test the effects of the present invention.

EXAMPLE 1

[0071] (i) Transmission coils having amorphous magnetic wires mountedthereon were prepared as the percutaneous electrical power transmissionsystem. Litz wire comprising bundles of 0.1 mm-diameter copper wire wasused for the windings. The coils were made to be donut-shaped, which isa shape that gives excellent heat dissipation, and three thousand Cozero magnetostrictive amorphous magnetic wires of expansion diameter 20μm were mounted radially on each coil. The magnetic wires were mountedon one side only of each coil, the coils were arranged such that thesurfaces on which magnetic wires were not mounted were facing oneanother, and electrical power was transmitted.

[0072] (ii) A rabbit (male; body weight 3 kg) was anesthetized, and thesecondary coil of the percutaneous electrical power transmission systemwas embedded below the skin on the right side of the chest.

EXAMPLE 2

[0073] (i) An embedded-within-body type artificial sphincter wasprepared by placing two shape memory alloy plates on top of one anotherand joining together the ends thereof at both ends. The shape memoryalloy plates were Ti—Ni alloy plates (Ni content 51 at %) that had beensubjected to heat treatment at 850° C. for 10 minutes, then restrainedin an arc shape of diameter 50 mm and subjected to aging treatment at400° C. for 100 hours; these plates exhibited shape memory effects inall directions; the dimensions were width 18.5 mm, length 70 mm andthickness 0.5 mm. The alimentary canal was to be inserted between thetwo shape memory alloy plates. Sponge rubber, which acts as heatinsulation and cushioning, was placed on the portions where the shapememory alloy plates would come into contact with the alimentary canal. Amedical silicone (Silastic MDX4-4210 made by Toray-Dow Silicone Asia)was applied onto the surfaces of the sponge rubber.

[0074] (ii) Heaters for heating were stuck to the outsides of the shapememory alloy plates, and a double layer of medical felt (Bard PTFE feltmade by Medicon) was stuck to the surface of each of the heaters so asto thermally insulate the body tissue from the artificial sphincter andobtain biocompatibility.

[0075] (iii) A live animal experiment was carried out using theartificial sphincter so prepared. A piglet 57, for which the structureof the alimentary system is similar to that of a human and the size ofthe alimentary canal is about the same as that of a human, was used inthe experiment. As shown in FIG. 10, the piglet 57 was put under generalanesthesia, then the abdomen was cut open, the rectum was severed, andone side of the rectum was led through the peritoneum to the abdominalwall and sewn on to form an artificial anus 51. Reference numeral 55 inFIG. 10 represents a temperature measuring device.

[0076] The shape memory alloy opening/closing portion 25, whichconstitutes the artificial sphincter of the present invention, wasinstalled between the peritoneum and the abdominal wall just below theartificial anus 51. Finally, the cut open part was sewn up completely.

[0077] (iv) A current was supplied to the shape memory alloyopening/closing portion 25 that constitutes the artificial sphincterfrom an electrical power supplying device 53 outside the body via a cord59. The artificial sphincter was opened 3 times a day by supplying acurrent to the artificial sphincter, thus carrying out defecation fromthe artificial anus 51.

[0078] (v) For 2 weeks after the installation of the artificialsphincter, the piglet showed normal feeding and defecation.

[0079] (vi) After 2 weeks, the piglet was dissected and observationsmade. A considerable amount of pus was found along the cord 59 used forsupplying the electrical current to the artificial sphincter. It isthought that an infection got in from outside the body along the cord59.

[0080] The cord 59 becomes unnecessary by providing the percutaneouselectrical power transmission system 33 so that the artificial sphinctercan be completely embedded into the living body. It is thereforepossible to prevent any infection through the cord 59.

[0081] As described above, with the artificial sphincter according tothe second embodiment of the present invention, an artificial anus canbe used without the risk of infection that is present if a tube orstimulating electrode is passed through the skin, and moreover in apsychologically favorable way.

[0082] Moreover, according to the second embodiment of the presentinvention, at low temperature the opening/closing portion is closed andthe intestine or the like is blocked off, but when electrical power issupplied to the opening/closing portion by means of a percutaneouselectrical power-transmission system, the opening/closing portion isheated and opens, and defecation occurs from the artificial anus.

[0083] In this way, according to the present invention, in addition tothe above-mentioned effects, because the shape memory alloyopening/closing portion comprises two shape memory alloy plates linkedtogether at both ends with hinges, there is no mechanism for a biasspring, which is indispensable in conventional SMA actuators, and hencethe artificial sphincter has a simple structure.

[0084] Moreover, according to the present invention, with regard to theplaces in which the artificial sphincter can be used, the artificialsphincter can, for example, open and close, as required, the anus of aliving body or part of the intestine led outside the body, or open andclose, as required, part of the urethra in a living body.

[0085] Moreover, according to the present invention, by additionallyproviding heat-insulating cushioning members on the inside and/or theoutside, the living body can be insulated from heat and cushioned, andmoreover, according to the present invention, by covering the artificialsphincter with a biocompatible material, care can be taken such thatthere will be no adverse effects on the surrounding body tissue.

[0086] Moreover, according to the present invention, the coils have aflat spirally wound structure, and due to this flatness do not take upmuch space, and according to the present invention as disclosed in claim8, a strong magnetic force can be obtained by mounting amorphousmagnetic wires.

[0087] Moreover, according to the present invention, the nuisance ofhaving to carry around a primary coil is eliminated, and situations suchas the primary coil being lost and it not being possible to obtain areplacement immediately are avoided.

[0088] Moreover, according to the present invention, a battery issuitable as the power source connected to the primary coil, and even ifthe secondary coil and the shape memory alloy opening/closing portionare installed in part of the body for which a general anesthetic isnecessary, the primary coil can be embedded in part of the body suchthat replacement is possible under only a local anesthetic.

What is claimed is:
 1. An artificial sphincter having an opening/closingportion for opening and closing, wherein said opening/closing portionhas a pair of elongated memory alloy elements that change reversiblybetween opposite shapes upon changes in temperature.
 2. The artificialsphincter according to claim 1, wherein said artificial sphincter isused for opening and closing, as required, either an anus of a livingbody or part of an intestine of a living body led outside said body. 3.The artificial sphincter according to claim 1, wherein said artificialsphincter comprises said pair of shape memory alloy elements and hingesthat link said pair of shape memory alloy elements together in acylindrical shape.
 4. The artificial sphincter according to claim 1,wherein said pair of shape memory alloy elements are plate-shaped, saidhinges being used to link said shape memory alloy elements together atboth ends thereof.
 5. The artificial sphincter according to claim 1,wherein said artificial sphincter has heat-insulating cushioning membersprovided at portions where either of said pair of shape memory alloyelements comes into contact with an intestine.
 6. The artificialsphincter according to claim 1, wherein said artificial sphincter hasheating members for heating said pair of shape memory alloy elements. 7.An artificial sphincter comprising a shape memory alloy opening/closingportion and temperature controlling heaters, wherein electrical power issupplied to said temperature controlling heaters by a percutaneouselectrical power transmission system having a coil on a side connectedto a power source as a primary coil and a coil on a side connected to aload as a secondary coil.
 8. The artificial sphincter according to claim7, wherein said shape memory alloy opening/closing portion comprises twoshape memory alloy plates linked together at both ends by hinges.
 9. Theartificial sphincter according to claim 7, wherein said shape memoryalloy opening/closing portion opens and closes, as required, either ananus of a living body or part of an intestine of a living body ledoutside said body.
 10. The artificial sphincter according to claim 7,wherein said shape memory alloy opening/closing portion opens andcloses, as required, part of a urethra in a living body.
 11. Theartificial sphincter according to claim 8, wherein heat-insulatingcushioning members are additionally provided on said two shape memoryalloy plates.
 12. The artificial sphincter according to claim 8, whereinsaid two shape memory alloy plates are covered with a biocompatiblematerial.
 13. The artificial sphincter according to claim 7, whereinsaid coils have a flat spirally wound structure.
 14. The artificialsphincter according to claim 13, wherein said coils have a flat spirallywound structure having mounted thereon amorphous magnetic wires.
 15. Theartificial sphincter according to claim 7, wherein said primary coil anda power supply are formed into a single integral body of a portabletype.
 16. The artificial sphincter according to claim 7, wherein saidsecondary coil, said temperature controlling heaters, and said shapememory alloy opening/closing portion are completely embedded in a livingbody.
 17. The artificial sphincter according to claim 7, wherein saidprimary coil is permanently installed in advance in a building or thelike.